This invention relates to a system for controlling a windfarm, and an apparatus and a method for controlling a windfarm.
Recently, there has been an increasing tendency for the introduction of wind power generation as a countermeasure against global warming. From the viewpoint of cost effect, the wind power generation finds its most prevalent form of practice in the “windfarm” wherein plural wind power generators are distributed in a specific area and all the generators are administrated together by a central station.
Since electricity cannot be stored basically, the amount of its generation must balance the amount of its consumption. If the balance between these amounts collapses, the frequency of the generated power will fluctuate. In the case of the wind power generation, whose power output fluctuates depending on the weather condition, the frequency of the output power is maintained constant by causing the amount of power generated by the generators of the thermal power stations within the power system to which the windfarm is connected, to follow the rate of change in the power demand. To be concrete, in order to cope with the change in the power demand, the governor-free control of generator is used for the short-term change within several minutes; the automatic load frequency control (LFC) is employed for the intermediate change from several minutes to about nineteen minutes; and the economic load dispatching control (EDC) is adopted for the long-term change for more than about nineteen minutes.
However, as the number of power generation stations increases, the adjustment of the voltage and the frequency of the power system becomes difficult. For example, there occurs a problem that the capacity of an automatic load frequency control (LFC) procedure becomes deficient when the load becomes lighter. Therefore, in order to promote the introduction of wind power generation while maintaining the quality of electric power at a satisfactory level, it is necessary to enhance the control capability on the side of the power system or to suppress the fluctuation of power generated by wind power generators.
For example, JP-A-2004-301116 discloses a method of controlling with high efficiency the operation of a wind power generation systems on the basis of the direction and velocity of wind blowing toward each windmill.
However, JP-A-2004-301116, which employs the procedure for suppressing the power fluctuation by using such an electric power storage device as accumulator batteries, will cause the entrepreneurs of wind power generation to suffer the burden of cost.